Environmental concerns pertaining to utilization of fossil fuels to generate electrical power together with the non-renewable nature of such fossil fuels have increased demand for alternative energy sources. Exemplary electrical power systems that utilize renewable energy resources include solar power systems, wind power systems, hydroelectric power systems, geothermal power systems, amongst others.
Conventional solar power systems, particularly those utilized to provide electrical power to a residence, include solar panels that comprise a plurality of relatively large silicon photovoltaic cells (e.g., approximately six inches by six inches). The solar cells are manufactured to output a certain voltage (regardless of an amount of solar radiation of particular wavelengths received at the solar cells). In an example, a conventional photovoltaic system can include a relatively small number (e.g., 100) of large cells. The cells are arranged in columns, and cells in the columns are connected in series to multiply the voltage from the individual cells to get a module of 10s of volts (e.g., 36 volts).
In a residential photovoltaic system installation, several columns are connected in series to obtain a voltage of approximately 200 volts, which is substantially optimal for commercial inverters. Series connected photovoltaic cells generate a voltage that is approximately equal to the sum of the voltages of the individual cells, but the current is approximately equal to the minimum current output by any of the photovoltaic cells. Since the current of a photovoltaic cell is proportional to the light that is incident on the cell, if one cell of a series connection receives a low light level, the entire series connection has a low current. Thus, a typical solar power system configuration that includes multiple columns can have a severe current reduction (and power output) when one cell or a portion of a cell has a low light level (e.g., due to shading). Oftentimes, when photovoltaic systems are installed on residences or other buildings, trees or other obstructions may be nearby, and accordingly shading of at least a portion of a module can occur frequently.